Grow Your Own Crystals Activity Source: Source: Mineralogical Society of America. Adapted with permission. Most minerals happen naturally as crystals. Crystals are made of specific atoms or molecules joined to make distinctive repeating patterns. The crystals that make up many kinds of minerals are formed deep underground through the interaction of fluid, pressure, and temperature. Some minerals form at or near the surface. You may have seen spectacular mineral samples in museums, but you might not be aware that minerals are everywhere, including in your body. [Read More]